feat(frontend): YouTube Music search, playback and playlist saving

frontend/src/routes/(app)/explore/+page.server.ts

@@ -1,14 +1,42 @@
-import type { PageServerLoad } from './$types';
-import { error } from '@sveltejs/kit';
+import type { PageServerLoad, Actions } from './$types';
+import { error, fail } from '@sveltejs/kit';
 import { createApiClient } from '$lib/server/api';
 
 const PAGE_SIZE = 24;
 
 export const load: PageServerLoad = async ({ url, locals, fetch }) => {
 	const query = url.searchParams.get('q')?.trim() ?? '';
+	const src = url.searchParams.get('src') === 'yt' ? 'yt' : ('local' as const);
 	const page = Math.max(1, Number(url.searchParams.get('page')) || 1);
 
 	const api = createApiClient({ fetch, accessToken: locals.accessToken ?? undefined });
+
+	if (src === 'yt') {
+		const emptyResults = { items: [], continuationToken: '' };
+
+		const playlistsPromise = locals.user
+			? api.GET('/playlists/users/{userId}', {
+					params: { path: { userId: locals.user.sub }, query: { pageNumber: 1, pageSize: 50 } }
+				})
+			: Promise.resolve(null);
+
+		const searchPromise =
+			query && locals.accessToken
+				? api.GET('/youtube/search', { params: { query: { query } } })
+				: Promise.resolve(null);
+
+		const [playlistsRes, searchRes] = await Promise.all([playlistsPromise, searchPromise]);
+
+		return {
+			src: 'yt' as const,
+			query,
+			ytResults: searchRes?.data ?? emptyResults,
+			ytError: Boolean(searchRes?.error),
+			playlists: playlistsRes?.data?.items ?? [],
+			needsAuth: !locals.user
+		};
+	}
+
 	const { data, error: err } = await api.GET('/tracks', {
 		params: { query: { name: query || undefined, pageNumber: page, pageSize: PAGE_SIZE } }
 	});
@@ -17,5 +45,38 @@ export const load: PageServerLoad = async ({ url, locals, fetch }) => {
 		error(502, 'No se pudieron cargar las canciones.');
 	}
 
-	return { tracks: data, query };
+	return { src: 'local' as const, query, tracks: data };
+};
+
+export const actions: Actions = {
+	addYouTubeToPlaylist: async ({ request, locals, fetch }) => {
+		if (!locals.accessToken) return fail(401, { message: 'Inicia sesión.' });
+
+		const form = await request.formData();
+		const playlistId = String(form.get('playlistId') ?? '');
+		const videoId = String(form.get('videoId') ?? '');
+		const title = String(form.get('title') ?? '');
+		const artist = String(form.get('artist') ?? '');
+		const durationSeconds = Number(form.get('durationSeconds') ?? 0);
+		const thumbnailUrl = String(form.get('thumbnailUrl') ?? '');
+
+		if (!playlistId || !videoId || !title) {
+			return fail(400, { message: 'Faltan datos de la canción.' });
+		}
+
+		const api = createApiClient({ fetch, accessToken: locals.accessToken });
+		const { error: err, response } = await api.POST('/playlists/{playlistId}/youtube-tracks', {
+			params: { path: { playlistId } },
+			body: { videoId, title, artist, durationSeconds, thumbnailUrl }
+		});
+
+		if (err) {
+			if (response?.status === 409) {
+				return fail(409, { message: 'La canción ya está en esa playlist.', videoId });
+			}
+			return fail(502, { message: 'No se pudo añadir la canción.', videoId });
+		}
+
+		return { added: true, videoId, playlistId };
+	}
 };